Error "No PairPotential given..."

[hsuya]

I am trying to perform the geometry optimization for mos2 monolayer using semi-empirical extended huckel method however it is showing this error in the log file, " No PairPotential given, which is required in order to calculate forces or stress." Also for Slater-Koster method there is no parameter file found. Please help.

[Petr Khomyakov]

You cannot do optimization using the Huckel method.

[hsuya]

Okay but the Slater Koster has missing parameters so i am not able to use that.

[Petr Khomyakov]

You may still try doing some DFT-LCAO calculations with computationally-cheap basis sets such as FHI-SZP or DZP.

[hsuya]

I tried using DFT-LCAO with FHI-DZP but it resulted in bond breaking.

[hsuya]

I am not able to understand what is going wrong...do I need to do something with the lattice parameters or what...

[Petr Khomyakov]

Your system is not really periodic, it is a 2D quantum dot - I suppose. You should consider increasing the in-plane lattice parameters and using non-periodic boundary conditions (Dirichlet and/or Neumann) in the Poisson solver settings to avoid interaction between periodic images.

In addition, there is no guarantee that your dot is unstable and would form some weird structure. Would it make more sense to put in on some substrate, instead of having it free-standing.